JP5119276B2 - Method for producing self-hardening mold molding sand composition and mold production method - Google Patents

Description

The present invention relates to a method for producing a self-hardening mold-making sand composition and a method for producing a mold.

  Conventionally, a self-hardening mold is known as one of casting molds. The self-hardening mold is obtained by adding and kneading a binder mainly composed of an acid curable resin and a curing agent such as xylene sulfonic acid or phosphoric acid to a refractory granular material such as silica sand, and then kneading. It is manufactured by filling sand with a mold and curing the binder.

  The acid curable resin is generally a resin mainly composed of furfuryl alcohol, urea, phenol, formaldehyde or the like, and is cured by polycondensation while dehydrating with an acid. The progress of curing of such an acid curable resin is affected by water generated by a dehydration reaction. That is, the surface portion that comes into contact with air tends to undergo a dehydration reaction and tends to harden. Accordingly, the self-hardening mold using the binder mainly composed of the acid curable resin has a difference in the degree of cure between the inside and the surface, and the strength is insufficient.

  Therefore, there is a method of reducing the difference in the degree of cure between the inside and the surface by using a large amount of sulfuric acid as an acid and increasing the overall curing rate. However, it is known that when a large amount of sulfuric acid is used, a cured product constituting the mold is thermally decomposed and sulfurous acid gas is generated during pouring of the obtained mold. Sulfurous acid gas deteriorates the working environment or inhibits casting spheroidization. Therefore, it is not preferable to use a large amount of sulfuric acid.

As a method of improving the strength of the mold without using sulfuric acid, there is a method of blending a chloride such as calcium chloride in a refractory granular material (see Patent Document 1).
In the method described in Patent Document 1, in order to absorb water generated by the dehydration reaction, a chloride such as calcium chloride is used in a powder form to absorb moisture. Furthermore, hydrochloric acid having a curing catalytic action is generated from the chloride to promote curing.

In addition, as a combination of a binder and a curing agent that can suppress the generation of sulfurous acid gas, maintain a good working environment, and mold a high-strength mold, an acid-curable resin and 2,5-bishydroxymethylfuran, etc. A binder composition containing a curing accelerator, a phosphorus-containing atom compound and a sulfur-containing atom compound, and a weight ratio of a sulfur atom content and a phosphorus atom content within a specific range Combinations with objects have been proposed (see, for example, Patent Document 2).
According to Patent Document 2, a decrease in the curing rate of the acid curable resin can be prevented by using a specific binder composition and a curing agent composition in combination. Furthermore, since the weight ratio of the sulfur-containing atomic compound in the curing agent composition is relatively small, generation of sulfurous acid gas can be suppressed and the working environment can be maintained well. In addition, a high-strength mold can be molded by using a phosphorus-containing atomic compound and a sulfur-containing primary atomic compound in combination as a curing agent.

Japanese Patent Publication No.51-3294 Japanese Patent No. 2826588

However, in Patent Document 1, it is necessary to mix the refractory granular material and the chloride in advance using a hopper or the like separately from the production line for obtaining the kneaded sand in order to mix the chloride powder. The manufacturing process has become complicated. Further, the chloride powder has a property of easily absorbing moisture. Therefore, there is a problem that it is difficult to manage in the factory in a powder state, and since it becomes a lump when it absorbs moisture, it is difficult to uniformly mix it in the refractory granular material.
As described above, the manufacturing method of Patent Document 1 has many inconveniences in manufacturing and is not practical, and has hardly been implemented.
In order to increase the curing speed, a method of directly adding hydrochloric acid having a curing catalytic action is also conceivable, but hydrochloric acid generates corrosive hydrogen chloride, which is difficult to store in a mold manufacturing factory, and is realistic. It wasn't.

Further, in Patent Document 1, since phosphoric acid is used to generate hydrochloric acid having a curing catalytic action from chloride, the characteristics of the refractory granular material are lowered, and the quality (strength) of the obtained mold may be lowered. .
Moreover, in patent document 2, since phosphoric acid or its salt is used as a phosphorus-containing atomic compound, the characteristic of a refractory granular material fell like patent document 1, and the quality of the casting_mold | template might fall.

The inventors of the present invention diligently studied the above problems, and prepared a binder by mixing an acid curable resin, water, and a solid metal chloride in advance. Mixing a refractory granular material and a hardener to make a sand composition, and using this sand composition to produce a mold can reduce the amount of sulfurous acid generated and is sufficient without complicating the production process. It has been found that a mold having a sufficient strength can be obtained. This binder can be stored in a container such as a storage tank, and can be taken out from the container and used in an amount necessary for producing a sand composition.
However, as a result of further investigations, it has been found that the binder may be separated into a water layer and a resin layer (layer separation). That is, layer separation may occur when the acid curable resin is mixed with chloride. When the binder is separated into layers, the chloride is dissolved in the aqueous layer, and a resin layer having a high specific gravity is located below the aqueous layer. Moreover, the binder stored in the container is often taken out from below the container. Therefore, when the binder stored in the container is separated into layers, a resin layer that does not contain enough chloride may be collected when the binder is removed from the container. It becomes difficult to manufacture things stably. The acid curable resin contains water derived from bound water generated in the synthesis process, but as the water content of the acid curable resin increases, layering of the binder tends to occur easily. I found out.

  The present invention has been made in view of the above circumstances, and even when an acid curable resin with a large amount of water is used, a generation amount of sulfurous acid gas can be reduced, and a mold having sufficient strength can be obtained without complicating the manufacturing process. It is an object of the present invention to provide a method for stably producing a mold molding sand composition that can be obtained, and a method for producing a mold.

The present invention has the following configuration.
[1] After preparing a mixture by mixing a refractory granular material, sulfonic acid and / or sulfuric acid, and simultaneously or after mixing an acid curable resin into the mixture, a calcium chloride solution and / or magnesium chloride The manufacturing method of the sand composition for self-hardening mold making which mixes a solution.
[2] A method for producing a self- hardening mold molding sand composition, wherein a refractory granular material, a sulfonic acid and / or sulfuric acid, an acid curable resin, and a calcium chloride solution and / or a magnesium chloride solution are simultaneously mixed.
[3] The acid curable resin is one or more of a condensate or a cocondensate of one or more selected from the group consisting of furfuryl alcohol, phenols and urea and an aldehyde, and The method for producing a self-hardening mold-making sand composition according to [1] or [2], which comprises furfuryl alcohol.
[4] The self-hardening mold-making sand composition according to any one of [1] to [3], wherein the solvent of the calcium chloride solution and the magnesium chloride solution is one or more selected from water and alcohol. Manufacturing method.
[5] The blending amount of the calcium chloride solution and / or the magnesium chloride solution is 0.005 to 0.150 parts by mass with respect to 100 parts by mass of the refractory granular material in terms of anhydrides. 4] The method for producing a self-hardening mold-making sand composition according to any one of [4].
[6] [1 ~ a self-hardening mold formation sand composition produced by the method according to any one of [5] was filled in a mold for casting molds manufacturing, curing the self-hardening mold formation sand composition A method for producing a mold.

  According to the present invention, even when an acid curable resin with a large amount of water is used, the amount of sulfurous acid gas generated can be reduced and a mold can be obtained with sufficient strength without complicating the production process. A method for stably producing a sand composition and a method for producing a mold can be provided.

Hereinafter, the present invention will be described in detail with reference to exemplary embodiments.
[Method for Producing Sand Composition for Mold Making]
The manufacturing method of the mold molding sand composition of the present embodiment example (hereinafter sometimes simply referred to as “sand composition”) includes an acid curable resin, a calcium chloride solution and / or a magnesium chloride solution, and fire resistance. Granular material and sulfonic acid and / or sulfuric acid are used.

The acid curable resin is a substance that is cured by polycondensation with an acid.
Examples of the acid curable resin include one or more of condensates or cocondensates of one or more selected from the group consisting of furfuryl alcohol, phenols and urea and aldehydes, and furfuryl alcohol. It is preferable to use those containing.

  Examples of aldehydes include formaldehyde, glyoxal, and furfural. You may use these in combination of 2 or more type. However, depending on the type of condensate, when glyoxal or furfural is used alone as an aldehyde, acid curing may not proceed. In such a case, at least formaldehyde may be used as the aldehyde.

  Examples of phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E, bisphenol F, and bisphenol Z. These may be used alone or in combination of two or more.

  Moreover, when manufacturing the condensate of phenols and aldehydes, it is preferable to use 1-3 mol of aldehydes with respect to 1 mol of phenols. If the amount of aldehyde used is 1 mol or more, it becomes a condensate with a low degree of polymerization, so that it is easy to set the pot life, and if it is 3 mol or less, it becomes a condensate with a high degree of polymerization. Good expression.

  When manufacturing the condensate of furfuryl alcohol and aldehydes, it is preferable to use 0.1-1 mol of aldehydes with respect to 1 mol of furfuryl alcohol. If the amount of aldehyde used is 0.1 mol or more, it becomes a condensate with a low degree of polymerization, so that the pot life can be easily set, and if it is 1 mol or less, it becomes a condensate with a high degree of polymerization. The final template strength is improved.

The nitrogen atom content derived from urea or the like is preferably in the range of 0.1 to 6% by mass per 100% by mass of the acid curable resin, and is preferably 0.1 to 4.5% by mass. It is more preferable that
The nitrogen atom content affects the initial strength and final strength of the template. When the nitrogen atom content is low, the initial strength of the template tends to be high, and when the nitrogen atom content is high, the template is high. The final strength of the steel tends to increase.
Accordingly, it is preferable to appropriately adjust the nitrogen atom content as necessary. If the nitrogen atom content is within the above range, a template having a favorable initial strength and final strength can be obtained.

The following four examples are particularly preferable for the acid curable resin. In addition, the (co) condensate in the following means a condensate and / or a cocondensate.
i) A mixture of a (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes with furfuryl alcohol.
ii) A mixture of urea and aldehyde condensate and furfuryl alcohol.
iii) A (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes, a mixture of phenol and aldehydes, and a mixture of furfuryl alcohol.
iv) A mixture of phenol and aldehyde condensate and furfuryl alcohol.

It is preferable that the acid curable resin is in such an embodiment of i) to iv) because a sand composition that can easily set the pot life and can improve the mold strength can be obtained.
In the aspect of i), the ratio of the (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes in the acid curable resin is preferably 15 to 45% by mass, and 25 to 35% by mass. Is more preferable. The ratio of furfuryl alcohol is preferably 55 to 85% by mass, and more preferably 65 to 75% by mass.
In the aspect of ii), the ratio of the condensate of urea and aldehydes in the acid curable resin is preferably 3.5 to 20% by mass, and more preferably 6.9 to 13.5% by mass. The ratio of furfuryl alcohol is preferably 80 to 96.5% by mass, and more preferably 86.5 to 93.1% by mass.
In the embodiment of iii), the ratio of the (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes in the acid curable resin is preferably 7.5 to 22.5% by mass, More preferably, it is 5 to 17.5% by mass. The ratio of the condensation product of phenol and aldehyde is preferably 7.5 to 22.5% by mass, and more preferably 12.5 to 17.5% by mass. The ratio of furfuryl alcohol is preferably 55 to 85% by mass, and more preferably 65 to 75% by mass.
In the aspect of iv), the ratio of the condensate of phenol and aldehyde in the acid curable resin is preferably 10 to 40% by mass, and more preferably 20 to 30% by mass. The ratio of furfuryl alcohol is preferably 60 to 90% by mass, and more preferably 70 to 80% by mass.

The acid curable resin can be obtained by a general production method. An example is shown below.
First, a part of the raw material of acid curable resin (furfuryl alcohol, aldehydes, urea, phenols, etc.) is mixed with an aqueous sodium hydroxide solution to make it alkaline, and the temperature is raised to produce a (co) condensate. . Next, it is acidified using hydrochloric acid or the like, and after a reaction such as a condensate of urea and aldehyde is allowed to proceed, it is made alkaline again, and the remaining acid curable resin raw materials are mixed to obtain an acid curable resin.
Since the amount of hydrochloric acid added here is small, it does not progress to the curing reaction.

  The acid curable resin thus obtained usually contains bound water derived from the synthesis of the (co) condensate. The amount of water of the acid curable resin varies depending on the conditions of the production method and the molecular weight of the acid curable resin, but in many cases, there are acid curable resins having a water content of 15% by mass or more.

The calcium chloride solution and the magnesium chloride solution serve as a supply source of hydrochloric acid (acid catalyst) having a curing catalytic action. Specifically, calcium chloride or magnesium chloride dissolved in a solvent (hereinafter sometimes collectively referred to as “chloride”) generates hydrochloric acid by contacting with sulfonic acid and / or sulfuric acid described later. Let
As the solvent for the calcium chloride solution and the magnesium chloride solution, it is preferable to use one or more solvents selected from water and alcohol. The alcohol is preferably a monovalent lower alcohol. In particular, methanol, ethanol, propanol, and the like are suitable because they are easily vaporized under the curing conditions of the acid-curable resin and can prevent the curing from being hindered.
Among these solvents, water, methanol, and ethanol are preferable because water is excellent in chloride solubility and the acid curable resin is more easily cured, and water is particularly preferable in terms of cost and workability. In addition, when using as a mixed solvent, the combination of water and alcohol may be sufficient, and the combination of different types of alcohol may be sufficient.

The calcium chloride solution and the magnesium chloride solution are difficult to determine the concentration range in general because the solubility of chloride differs depending on the type of solvent, but usually 20 to 70% by mass is preferable, and 30 to 60% by mass is preferable. More preferred. When the concentration is 20% by mass or more, the acid curable resin is sufficiently cured. On the other hand, if the concentration is 70% by mass or less, it is possible to suppress precipitation of chloride from the sand composition particularly in a low temperature environment.
In the present invention, “concentration” means the amount (% by mass) of chloride in 100% by mass of the solution.

As the refractory granular material, conventionally known materials such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Recycled ones can also be used.
In particular, it is preferable to use chromite sand, zircon sand, and alumina sand for a portion that requires fire resistance, and among them, it is preferable to use alumina sand that does not cost and has no problem with disposal.

As described above, the chloride dissolved in the solvent generates hydrochloric acid by contacting with sulfonic acid and / or sulfuric acid. The generated hydrochloric acid accelerates the curing of the acid curable resin, and a sand composition capable of obtaining a high-strength mold can be produced.
In the present invention, the “sulfonic acid” is an organic compound in which a sulfo group is substituted with a carbon skeleton. Examples of the sulfonic acid include xylene sulfonic acid and paratoluene sulfonic acid.

Sulfuric acid and sulfuric acid tend to be faster in sulfuric acid than in sulfonic acid when compared in terms of curing speed. On the other hand, when compared with curing strength, sulfonic acid tends to be stronger than sulfuric acid.
Therefore, in the present invention, sulfonic acid and sulfuric acid may be used in consideration of the balance between the initial strength and final strength of the mold, the generation of sulfurous acid gas, and the like. The sulfonic acid and sulfuric acid may be used alone or in combination, but it is preferable to use them together. When used in combination, the mass ratio of sulfonic acid to sulfuric acid is preferably sulfonic acid: sulfuric acid = 1: 2 to 20: 1.

  In the present invention, in addition to the components described above, a silane coupling agent such as N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane may be used for the purpose of improving the strength of the obtained template.

In the present invention, the acid curable resin, the calcium chloride solution and / or the magnesium chloride solution, the refractory granular material, and the sulfonic acid and / or sulfuric acid are mixed in the procedure A or the procedure B described later. A sand composition is produced.
The compounding amount of the acid curable resin is preferably 0.3 to 2.0 parts by mass, and more preferably 0.5 to 1.0 part by mass with respect to 100 parts by mass of the refractory granular material. If the compounding amount of the acid curable resin is 0.3 parts by mass or more, a sufficiently strong mold can be easily obtained. On the other hand, if the compounding amount of the acid curable resin is 2.0 parts by mass or less, the mold after pouring can be easily disassembled.

The blending amount of the calcium chloride solution and / or the magnesium chloride solution is preferably 0.005 to 0.150 parts by mass, and 0.0075 to 0.0600 parts per 100 parts by mass of the refractory granular material in terms of anhydride. More preferably, it is part by mass. If the blending amount of the calcium chloride solution and / or the magnesium chloride solution is 0.005 parts by mass or more in terms of anhydride, the amount of sulfurous acid gas generated can be effectively reduced. In addition, although the reduction effect of the generation amount of sulfurous acid gas becomes so large that the compounding quantity of a calcium chloride solution and / or a magnesium chloride solution increases, on the other hand, it exists in the tendency for the intensity | strength of a casting_mold | template to fall. Since it is sufficient for the mold to have a strength of 2.50 N / mm ² or more, the upper limit of the blending amount of the calcium chloride solution and / or the magnesium chloride solution is 0.150 mass to maintain this level of strength. Part. In particular, when the blending amount is 0.0075 to 0.0600 parts by mass, the strength of the mold is further improved in addition to the reduction in the amount of sulfurous acid gas generated.

  The amount of the sulfonic acid and / or sulfuric acid is preferably 0.045 to 1.200 parts by mass, more preferably 0.075 to 0.900 parts by mass with respect to 100 parts by mass of the refractory granular material. When the blending amount of sulfonic acid and / or sulfuric acid is within the above range, a template having sufficient strength can be easily obtained.

  Moreover, when using a silane coupling agent, it is preferable that the compounding quantity is 0.0005-0.01 mass part with respect to 100 mass parts of refractory granular materials, 0.001-0.005 mass part More preferably. If the compounding quantity of a silane coupling agent is 0.0005 mass part or more, the intensity | strength of a casting_mold | template can be improved. On the other hand, if the compounding amount of the silane coupling agent is 0.01 parts by mass or less, a significant cost increase can be suppressed.

  The mixing method is not particularly limited as long as it is a general mixing method, and examples thereof include a method of mixing using a stirrer.

The mixing procedure is as follows.
Procedure A: After preparing a mixture by mixing a refractory granular material and sulfonic acid and / or sulfuric acid, and simultaneously or after mixing the acid curable resin with the mixture, a calcium chloride solution and / or magnesium chloride Mix the solution.
Procedure B: Refractory granular material, sulfonic acid and / or sulfuric acid, acid curable resin, calcium chloride solution and / or magnesium chloride solution are mixed simultaneously.

In both the procedure A and the procedure B, the refractory granular material and the sulfonic acid and / or sulfuric acid are present at the timing when the acid curable resin and the chloride are mixed. As described above, the amount of the solid refractory granular material is larger than that of other liquid components. Therefore, procedures A and procedure B are both in the high solid body of the amount, it means that mix is small amount liquid, does not occur phase separation. Therefore, a sand composition can be stably produced even when an acid curable resin having a high water content as an acid curable resin, that is, an acid curable resin that easily separates (layer separation) into a water layer and a resin layer when mixed with chloride is used.
Therefore, the present invention is also suitable when an acid curable resin having a large water content, particularly a water content of 15% by mass or more is used as the acid curable resin.

In both procedure A and procedure B, the acid-curable resin is present at the timing when the chloride contacts the acid (sulfonic acid and / or sulfuric acid). Therefore, the sand composition which can manufacture the casting_mold | template which has sufficient intensity | strength and was excellent in the initial stage strength especially by performing the procedure A or the procedure B can be manufactured. The reason for this is considered as follows.
When the chloride comes into contact with the acid, hydrochloric acid having a curing catalytic action is generated by a metathesis reaction. If acid curable resin is present when hydrochloric acid is generated, the generated hydrochloric acid can be efficiently used for curing the acid curable resin, so that a sand composition capable of producing a mold having particularly excellent initial strength can be manufactured. It is considered possible.

  In the case of the procedure A, the timing of mixing the acid curable resin and the calcium chloride solution and / or the magnesium chloride solution into the mixture may be the same, or after mixing the acid curable resin, the calcium chloride solution and / or the magnesium chloride solution. May be mixed. In particular, if the acid curable resin is mixed with the mixture and then mixed with the calcium chloride solution and / or the magnesium chloride solution, the addition of all the acid curable resin is completed when hydrochloric acid is generated. The curable resin can uniformly contact hydrochloric acid. Therefore, hydrochloric acid can be used more efficiently for curing the acid curable resin, and a mold having better initial strength can be obtained.

  In addition, it is conceivable to mix a calcium chloride solution and / or a magnesium chloride solution into the mixture before mixing the acid curable resin into the mixture, but in this case, the metathesis reaction by chloride and acid proceeds immediately after mixing. Will be. As a result, a large amount of hydrochloric acid having a curing catalytic action is generated and released out of the system. Even if the acid curable resin is mixed later in such a state, the concentration of hydrochloric acid in the system is lowered, so that the curing does not proceed sufficiently and the initial strength of the mold is considered to be lowered.

By the way, in the case of the procedure A, since the refractory granular material and sulfonic acid and / or sulfuric acid are mixed in advance, the surface of the refractory granular material is coated with sulfonic acid and / or sulfuric acid. As a result, it is considered that sulfonic acid and / or sulfuric acid is uniformly dispersed in the mixture. When the acid curable resin is added to the mixture in such a state, the acid curable resin is likely to be localized in the mixture immediately after the addition, but it is possible to suppress the rapid progress of the curing acceleration reaction. The reason for this is considered as follows.
Immediately after the acid curable resin is added to the mixture, the acid curable resin is not uniformly dispersed, so that the acid curable resin is likely to be localized in the mixture. However, since the sulfonic acid and / or sulfuric acid is uniformly dispersed in the mixture, even if the amount of the acid curable resin is locally increased, the sulfonic acid and / or sulfuric acid with respect to the ratio of the acid curable resin. The ratio is small. Therefore, it is thought that it can suppress that hardening acceleration reaction advances rapidly. When the acid curable resin is added to the mixture and then mixed, the acid curable resin is uniformly dispersed in the mixture. As a result, since the ratio of the sulfonic acid and / or sulfuric acid to the acid curable resin becomes uniform, the curing acceleration reaction proceeds uniformly.

The calcium chloride solution and / or the magnesium chloride solution is the same as the acid curable resin.
That is, when a calcium chloride solution and / or a magnesium chloride solution is added to the mixture simultaneously with the acid curable resin or after the acid curable resin is added, the calcium chloride solution and / or the magnesium chloride solution is added to the mixture in the mixture immediately after the addition. Easy to exist. However, since sulfonic acid and / or sulfuric acid are uniformly dispersed in the mixture, the ratio of sulfonic acid and / or sulfuric acid is small with respect to the ratio of calcium chloride solution and / or magnesium chloride solution. Therefore, it is considered that the rapid progress of the metathesis reaction can be suppressed.
Then, after adding the calcium chloride solution and / or the magnesium chloride solution to the mixture and mixing them, the calcium chloride solution and / or the magnesium chloride solution are uniformly dispersed in the mixture, so that the metathesis reaction proceeds uniformly. .

  Therefore, in the present invention, a refractory granular material, sulfonic acid and / or sulfuric acid are able to produce a mold particularly excellent in initial strength, and can suppress the rapid progress of curing acceleration reaction or metathesis reaction. The procedure of mixing the calcium curable solution and / or the magnesium chloride solution after the acid curable resin is mixed with the mixture is most preferable.

In either case, Procedure A and Procedure B are not limited in timing for adding the silane coupling agent.
In the case of the procedure A, the silane coupling agent may be blended in the mixture, or may be added to the mixture together with the acid curable resin, the calcium chloride solution and / or the magnesium chloride solution and mixed. Alternatively, a silane coupling agent may be blended in advance with the acid curable resin, and this may be added to the mixture.
In the case of the procedure B, the silane coupling agent may be added in accordance with the mixing timing of each component, or may be blended in advance with the acid curable resin.

According to the present invention, the generation amount of sulfurous acid gas can be reduced without avoiding the use of sulfuric acid or sulfonic acid, or without intentionally reducing the amount of use thereof. The reason for this is considered as follows.
That is, in the present invention, chloride dissolved in a solvent comes into contact with an acid (sulfonic acid and / or sulfuric acid) to undergo a metathesis reaction to generate hydrochloric acid having a curing catalytic action, and calcium sulfate and magnesium sulfate are generated. Is done. The thermal decomposition temperature of calcium sulfate or magnesium sulfate is 1100 ° C. or higher and is thermally stable, so it is not easily decomposed, and it is considered that sulfurous acid gas is hardly generated.
Therefore, according to the sand composition obtained by the present invention, a high-strength mold can be produced by generating hydrochloric acid having a curing catalytic action, and the obtained mold is heated to a high temperature (usually about 1000 ° C.). Thus, even if the liquid material is poured, the cured product constituting the mold is not easily decomposed, and the amount of sulfurous acid gas generated can be reduced.

  In the present invention, a calcium chloride solution and / or a magnesium chloride solution is used as the chloride. That is, since the chloride is handled in a state dissolved in a solvent, it is not necessary to control the humidity at the mold manufacturing site so that the chloride does not absorb moisture. Moreover, it is not necessary to complicate the process for obtaining the sand composition.

Furthermore, in the present invention, since a calcium chloride solution and / or a magnesium chloride solution is used as a hydrochloric acid supply source, it can be easily mixed with other components more uniformly than when solid calcium chloride or magnesium chloride is used.
It should be noted that calcium chloride and magnesium chloride cannot exhibit a curing accelerating action as they are in a solid state, but exhibit a curing accelerating action by generating hydrochloric acid in contact with an acid in a dissolved state in water or the like. Can do. As described above, the acid curable resin contains water derived from bound water in the production process. Therefore, even if solid calcium chloride or magnesium chloride is used, any of them is dissolved in the sand composition, and hydrochloric acid can be generated by contact with an acid. However, when solid calcium chloride or magnesium chloride is used, they are difficult to uniformly disperse or dissolve in the sand composition, and as a result, the amount of sulfurous acid gas generated cannot be sufficiently reduced. is there. Therefore, when solid calcium chloride or magnesium chloride is used, it is necessary to sufficiently mix them so that they are uniformly dispersed and dissolved in the sand composition, and workability is likely to deteriorate. . Also, since it takes time for solid calcium chloride and magnesium chloride to dissolve in the sand composition, it is necessary to wait until the sand composition is ready for use. It is unsuitable. In addition, when preparing a binder by mixing chloride with an acid curable resin, if solid calcium chloride or magnesium chloride is used, these may be uniformly dispersed or dissolved in the binder. It is difficult to mix well.

  On the other hand, according to the present invention, since it is used in a state in which chloride is already dissolved, it can be easily mixed uniformly with other components, and there is no possibility of precipitation or separation in the sand composition. Moreover, if it is this invention, it is not necessary to consider the time for calcium chloride or magnesium chloride to dissolve in the sand composition. Therefore, the sand composition can be manufactured in accordance with the timing of manufacturing the mold, and the obtained sand composition can be used immediately.

  The sand composition thus obtained can obtain a mold having sufficient strength while reducing the amount of sulfurous acid gas generated during the production of the mold.

[Mold manufacturing method]
In the mold production method of the present invention, the sand composition produced by the above-described method is used, the sand composition is filled in a mold for mold production, and the sand composition is cured to produce the mold.
As a method for producing the mold, a self-hardening mold making method can be employed. That is, when the sand composition is filled in a predetermined mold for mold making, the sand composition is cured by the action of the curing agent. As a result, a template can be obtained.
In the method for producing a mold of the present invention, a sand composition produced using a calcium chloride solution and / or a magnesium chloride solution is used. In the sand composition, calcium chloride and / or magnesium chloride is uniformly dispersed in the sand composition, and as soon as the dissolved calcium chloride and / or magnesium chloride comes into contact with an acid (sulfonic acid and / or sulfuric acid). It reacts to generate hydrochloric acid having a curing catalytic action, so that not only the surface of the mold but also the inside is cured well, and the strength of the mold can be further improved.

In addition, when hydrochloric acid having a curing catalytic action is generated from a calcium chloride solution and / or a magnesium chloride solution, calcium sulfate and magnesium sulfate are also generated. However, since these are thermally stable, sulfurous acid gas is generated. It is considered difficult.
Therefore, according to the present invention, a cured product that constitutes the mold when pouring into the mold obtained from the sand composition of the present invention without using a phosphorus-containing atomic compound such as phosphoric acid or a salt thereof as a curing agent. Is difficult to thermally decompose, and the amount of sulfurous acid gas generated can be reduced. Therefore, a good working environment can be obtained, and at the same time, the occurrence rate of mineral spheroidization inhibition due to sulfur in sulfurous acid gas can be reduced.
Furthermore, since no phosphorus-containing atomic compound is used in the present invention, there is no fear that the characteristics of the refractory granular material will deteriorate, and the quality (strength) of the obtained mold can be maintained well.

Further, according to the present invention, even if alumina sand is used as the refractory granular material, it is possible to obtain a mold strength equivalent to that when using conventional silica sand while reducing the amount of generated sulfurous acid gas. It is considered to be.
Alumina sand has attracted attention as a refractory granular material for molds because of its high fire resistance and excellent crushing resistance. However, since its heat capacity is larger than that of silica sand, which is a conventional refractory granular material, a mold manufactured using this material is used. Has a slow curing rate and tends to increase the difference in the degree of cure between the inside and the surface, making it difficult to obtain strength and difficult to put into practical use.
However, since the sand composition obtained by the present invention can improve not only the mold surface but also the internal curing, it can improve the initial strength of the mold and the strength after a long time, so that the heat capacity is high. Even when a refractory granular material such as large alumina sand is used, a mold strength equivalent to that obtained when conventional silica sand is used can be obtained. Therefore, it is considered that the mold can be produced even with a refractory granular material having a high heat capacity such as alumina sand.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. In addition, the composition of the sand composition used in each Example and Comparative Example and each physical property of the obtained mold (test piece) were measured by the following methods.

(Measurement of water content)
The water content was determined by the moisture test method for chemical products of JIS K 0068.

(Measurement of nitrogen atom content)
The nitrogen atom content was determined by the titration method of the factory wastewater test method of JIS K 0102.

(Measurement of compressive strength)
For the compressive strength (mold strength) of the test pieces obtained in each of the examples and comparative examples, use a desktop counter pressure tester (manufactured by Takachiho Kikai Co., Ltd.) according to the testing method for foundry sand of JIS Z 2601. Measured with

(Measurement of bulk density)
The bulk density of the test pieces obtained in each Example and Comparative Example was determined by the following general formula (I). METLER PM 4000 (manufactured by Nippon Shibel Hegner Co., Ltd.) was used as an electronic balance used for mass measurement.
The bulk density is measured to confirm that the wooden mold is filled with approximately the same mass of kneaded sand.
Test piece bulk density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ ) (I)

(Measurement of the amount of sulfur dioxide generated)
After disassembling the test pieces obtained in each Example and Comparative Example, 5 g was collected and exposed under a temperature condition of 1000 ° C., and the gas generated therefrom was collected in a 10 L tetra bag and collected. The gas was analyzed with a Kitagawa type detector tube and the amount of sulfurous acid gas generated was measured.

[Example 1-1]
(Preparation of acid curable resin (I))
859.20 parts by mass of furfuryl alcohol, 47.05 parts by mass of urea, 65.90 parts by mass of paraformaldehyde of 92% by mass, and 2.00 parts by mass of a 15% by mass aqueous sodium hydroxide solution The mixture was placed in a four-necked flask equipped with a stirrer and reacted at 80 ° C. for 1 hour. Thereafter, 3.00 parts by mass of 10% by mass hydrochloric acid was added, and further reacted for 3 hours. Thereafter, 2.00 parts by mass of a 15% by mass aqueous sodium hydroxide solution and 28.84 parts by mass of urea were added and reacted for another 30 minutes. Thereafter, a silane coupling agent (N-β (aminoethyl) γ- 2.00 parts of (aminopropylmethyldimethoxysilane) was added to obtain 1010 parts by mass of acid curable resin (I) to which a silane coupling agent had been added. The water content (water content) in 1010 parts by mass of the acid curable resin (I) is 4.5% by mass, and the nitrogen atom content relative to the total amount of the acid curable resin (I) and water is 3. It was 5 mass%.

(Manufacture of sand composition)
100 parts by mass of silica sand (manufactured by Mitsubishi Corporation Building Materials Co., Ltd., free mantle new sand), 0.80 part by mass of the silane coupling agent-added acid curable resin (I), and 50% by mass calcium chloride aqueous solution 0.01 Mass parts (0.005 parts by mass in terms of anhydride) and 0.32 parts by mass of a 75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid were added simultaneously, and a Shinagawa universal agitator (MIXER , Manufactured by Shinagawa Kogyo Co., Ltd.) to obtain a sand composition.

(Manufacture of test pieces)
The obtained sand composition is filled in a wooden piece for test piece preparation in which a mold having an inner diameter of 50 mm and a height of 50 mm is formed under conditions of a temperature of 25 ° C. and a humidity of 60%, and 24 hours have elapsed since the start of curing. The test piece was taken out later.
The obtained test piece was measured for compressive strength and bulk density. Moreover, the test piece was disassembled and the amount of sulfurous acid gas generated was measured. The results are shown in Table 1. In addition, the generation amount of sulfurous acid gas was represented by the value when the measurement result of Comparative Example 1-1 described later is 100%.

[Example 1-2]
A sand composition was produced and obtained in the same manner as in Example 1-1, except that the amount of the 50% by mass calcium chloride aqueous solution was changed to 0.06 parts by mass (0.030 parts by mass in terms of anhydride). A test piece was manufactured using the sand composition, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Example 1-3]
A sand composition was produced and obtained in the same manner as in Example 1-1 except that the amount of the 50% by mass calcium chloride aqueous solution was changed to 0.10 parts by mass (0.050 parts by mass in terms of anhydride). A test piece was manufactured using the sand composition, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Example 1-4]
A sand composition was produced and obtained in the same manner as in Example 1-1, except that the blending amount of the 50% by mass calcium chloride aqueous solution was changed to 0.30 parts by mass (0.150 parts by mass in terms of anhydride). A test piece was manufactured using the sand composition, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Example 1-5]
A sand composition was prepared in the same manner as in Example 1-1, except that 0.01 parts by mass (0.005 parts by mass in terms of anhydride) of 50% by mass magnesium chloride aqueous solution was blended instead of the 50% by mass calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Example 1-6]
A sand composition was prepared in the same manner as in Example 1-1 except that 0.06 parts by mass (0.030 parts by mass in terms of anhydride) of 50% by mass magnesium chloride aqueous solution was blended in place of the 50% by mass calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Example 1-7]
A sand composition was prepared in the same manner as in Example 1-1, except that 50 mass% magnesium chloride aqueous solution was mixed with 0.10 mass parts (0.050 mass parts in terms of anhydride) instead of the 50 mass% calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Example 1-8]
A sand composition was prepared in the same manner as in Example 1-1 except that 0.30 parts by mass (0.150 parts by mass in terms of anhydride) of 50% by mass magnesium chloride aqueous solution was added instead of the 50% by mass calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

[Comparative Example 1-1]
A sand composition was produced in the same manner as in Example 1-1 except that a 50% by mass calcium chloride aqueous solution was not blended. A test piece was produced using the obtained sand composition, and the compressive strength and bulk density were obtained. , And the amount of sulfurous acid gas generated was measured. The results are shown in Table 1.

[Comparative Example 1-2]
To 100 parts by mass of silica sand, 0.04 part by mass of calcium chloride dihydrate is added, and kneaded with a Shinagawa universal stirrer to mix 100.04 parts by mass of calcium chloride-containing sand (0.030 mass of calcium chloride in terms of anhydride). Part contained).
75% by mass containing 0.80 part by mass of the above-mentioned silane coupling agent-added acid curable resin (I), 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid in 100.04 parts by mass of calcium chloride-containing sand 0.32 parts by mass of an aqueous solution was added simultaneously and kneaded with a Shinagawa universal stirrer to obtain a sand composition.
A test piece was produced in the same manner as in Example 1-1 except that the obtained sand composition was used, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 1.

  In Table 1, the blending amounts of the 50 mass% calcium chloride aqueous solution and the 50 mass% magnesium chloride aqueous solution in Examples 1-1 to 1-8 and Comparative Example 1-1 are based on 100 parts by mass of the refractory granular material (silica sand). The amount of calcium chloride or magnesium chloride in terms of anhydride. In addition, in the case of the comparative example 1-2, the quantity of the calcium chloride dihydrate converted into the anhydride with respect to 100 mass parts of refractory granular materials (silica sand) was shown.

As is clear from Table 1, in Examples 1-1 to 1-4 in which a sand composition was produced by blending a 50 mass% calcium chloride aqueous solution, the amount of sulfurous acid gas generated could be reduced. Moreover, the compressive strength of intensity | strength sufficient as a casting_mold | template was shown.
The compressive strength tended to decrease as the blending amount of the 50% by mass calcium chloride aqueous solution increased. Further, the amount of sulfurous acid gas generated tended to be reduced as the blending amount of the 50 mass% calcium chloride aqueous solution increased.

In Examples 1-5 to 1-8 in which a sand composition was prepared by blending a 50 mass% magnesium chloride aqueous solution, the amount of sulfurous acid gas generated could be reduced. Moreover, the compressive strength of intensity | strength sufficient as a casting_mold | template was shown.
The compressive strength tended to decrease as the blending amount of the 50 mass% magnesium chloride aqueous solution increased. Further, the amount of sulfurous acid gas generated tended to be reduced as the blending amount of the 50 mass% magnesium chloride aqueous solution increased.

On the other hand, Comparative Example 1-1 in which the sand composition was produced without blending the 50 mass% calcium chloride aqueous solution showed a compressive strength sufficient as a mold as in Examples 1-1 to 1-8. The effect of reducing the amount of sulfurous acid gas generated was not obtained.
In Comparative Example 1-2, silica sand and calcium chloride dihydrate were mixed, and then an acid-curable resin, an aqueous solution containing xylene sulfonic acid and sulfuric acid were added thereto to produce a sand composition. Since it was solid, it was difficult to uniformly disperse or dissolve in the sand composition. Therefore, metathesis reaction hardly occurred, and the compression strength of the mold was low as compared with Examples 1-2 and 1-6. Moreover, the effect of reducing the amount of sulfurous acid gas generated was not obtained.

[Example 2-1]
(Preparation of acid curable resin (II))
When adding 2.00 parts of silane coupling agent, except that 124.8 parts by mass of water was added, the same as in Example 1-1, the acid curable resin (II) to which the silane coupling agent had been added 1134.8 mass parts was obtained. The water content in 1134.8 parts by mass of the acid curable resin (II) is 15.0% by mass, and the nitrogen atom content with respect to the total amount of the acid curable resin (II) and water is 3.1% by mass. there were.

(Manufacture of sand composition)
To 100 parts by mass of silica sand, 0.32 parts by mass of a 75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid was added and kneaded for 1 minute with a Shinagawa universal agitator to obtain a mixture.
To the obtained mixture, 0.80 part by mass of the silane coupling agent-added acid curable resin (II) is added, and then 50 parts by mass of a 50% by mass calcium chloride aqueous solution (0.005 in terms of anhydride). Mass part) was added, and a sand composition was obtained by continuous for 1 minute using a Shinagawa universal stirrer.

(Manufacture of test pieces)
A test piece was produced in the same manner as in Example 1-1 except that the obtained sand composition was used, and the compression strength, bulk density, and generation amount of sulfurous acid gas were measured. Table 2 shows the results. In addition, the generation amount of sulfurous acid gas was represented by the value when the measurement result of Comparative Example 2-1 described later is 100%.

[Example 2-2]
A sand composition was produced and obtained in the same manner as in Example 2-1, except that the amount of the 50% by mass calcium chloride aqueous solution was changed to 0.06 parts by mass (0.030 parts by mass in terms of anhydride). A test piece was manufactured using the sand composition, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Example 2-3]
A sand composition was produced and obtained in the same manner as in Example 2-1, except that the amount of the 50% by mass calcium chloride aqueous solution was changed to 0.10 parts by mass (0.050 parts by mass in terms of anhydride). A test piece was manufactured using the sand composition, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Example 2-4]
A sand composition was produced and obtained in the same manner as in Example 2-1, except that the amount of the 50% by mass calcium chloride aqueous solution was changed to 0.30 parts by mass (0.150 parts by mass in terms of anhydride). A test piece was manufactured using the sand composition, and the compressive strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Example 2-5]
A sand composition was prepared in the same manner as in Example 2-1, except that 0.01 parts by mass (0.005 parts by mass in terms of anhydride) of 50% by mass magnesium chloride aqueous solution was blended instead of the 50% by mass calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Example 2-6]
Sand composition in the same manner as in Example 2-1, except that 0.06 parts by mass (0.030 parts by mass in terms of anhydride) of 50% by mass magnesium chloride aqueous solution was blended in place of the 50% by mass calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Example 2-7]
A sand composition was prepared in the same manner as in Example 2-1, except that 50 mass% magnesium chloride aqueous solution was added in an amount of 0.10 mass parts (0.050 mass parts in terms of anhydride) instead of the 50 mass% calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Example 2-8]
A sand composition was prepared in the same manner as in Example 2-1, except that 0.30 parts by mass (0.150 parts by mass in terms of anhydride) of 50% by mass magnesium chloride aqueous solution was blended in place of the 50% by mass calcium chloride aqueous solution. A test piece was produced using the obtained sand composition, and the compression strength, bulk density, and amount of sulfurous acid gas generated were measured. The results are shown in Table 2.

[Comparative Example 2-1]
A sand composition was produced in the same manner as in Example 2-1, except that a 50 mass% calcium chloride aqueous solution was not blended. A test piece was produced using the obtained sand composition, and the compressive strength and bulk density were obtained. , And the amount of sulfurous acid gas generated was measured. The results are shown in Table 2.

[Comparative Example 2-2]
An attempt was made to produce a sand composition by previously mixing an acid curable resin and chloride and adding this to the mixture obtained in Example 2-1.
Therefore, first, 0.80 part by mass of acid-curable resin (II) to which a silane coupling agent has been added and 0.04 part by mass of calcium chloride dihydrate (0.030 part by mass in terms of anhydride) are mixed. did.
However, the sand composition was not manufactured because it was separated into an aqueous layer and a resin layer.

  In Table 2, the compounding amounts of the 50 mass% calcium chloride aqueous solution and the 50 mass% magnesium chloride aqueous solution are shown in terms of anhydride relative to 100 parts by mass of the refractory granular material (silica sand).

As apparent from Table 2, in Examples 2-1 to 2-4 in which the sand composition was prepared by blending the 50 mass% calcium chloride aqueous solution, the amount of sulfurous acid gas generated could be reduced. Moreover, the compressive strength of intensity | strength sufficient as a casting_mold | template was shown.
The compressive strength tended to decrease as the blending amount of the 50% by mass calcium chloride aqueous solution increased. Further, the amount of sulfurous acid gas generated tended to be reduced as the blending amount of the 50 mass% calcium chloride aqueous solution increased.

Moreover, in Examples 2-5 to 2-8 in which a sand composition was prepared by blending a 50 mass% magnesium chloride aqueous solution, the amount of sulfurous acid gas generated could be reduced. Moreover, the compressive strength of intensity | strength sufficient as a casting_mold | template was shown.
The compressive strength tended to decrease as the blending amount of the 50 mass% magnesium chloride aqueous solution increased. Further, the amount of sulfurous acid gas generated tended to be reduced as the blending amount of the 50 mass% magnesium chloride aqueous solution increased.

On the other hand, in Comparative Example 2-1, in which the sand composition was produced without blending the 50 mass% calcium chloride aqueous solution, the compressive strength sufficient as a mold was shown as in Examples 2-1 to 2-8. The effect of reducing the amount of sulfurous acid gas generated was not obtained.
In Comparative Example 2-2, since the acid curable resin (II) having a high water content of 15.0% by mass and calcium chloride dihydrate were mixed, the acid curable resin (II) was precipitated, It separated into a resin layer. In addition, although Comparative Example 2-2 is an example using solid calcium chloride, it is considered that layer separation similarly occurs even when liquid calcium chloride or magnesium chloride is used.

[Experimental example]
Hereinafter, experimental examples will be described.
In Examples 1 to 5 below, alumina sand was used as the refractory granular material in order to confirm that the effect of improving the strength of the mold was obtained regardless of the type of the refractory granular material according to the present invention. In this case, the compression strength of the mold was measured.
Since the strength of the template is considered to be hardly affected by the state of chloride (solid or liquid), the experiment was conducted using solid calcium chloride for convenience.
In addition, for the sake of convenience, the experiment was performed using a binder prepared by adding solid calcium chloride to an acid curable resin in advance. However, the strength of the mold is determined by adding chloride to the acid curable resin in advance. Will not be damaged. The binder was prepared using an acid curable resin having a water content that does not cause a problem of layer separation.

<Experimental example 1>
(Preparation of binder)
859.20 parts by mass of furfuryl alcohol, 47.05 parts by mass of urea, 65.90 parts by mass of paraformaldehyde of 92% by mass, and 2.00 parts by mass of a 15% by mass aqueous sodium hydroxide solution The mixture was placed in a four-necked flask equipped with a stirrer and reacted at 80 ° C. for 1 hour. Thereafter, 3.00 parts by mass of 10% by mass hydrochloric acid was added, and further reacted for 3 hours. Thereafter, 2.00 parts by mass of a 15% by mass aqueous sodium hydroxide solution and 28.84 parts by mass of urea were added and reacted for another 30 minutes. Thereafter, a silane coupling agent (N-β (aminoethyl) γ- 2.00 parts of aminopropylmethyldimethoxysilane) was added to obtain 1010 parts by mass of acid curable resin (III) to which a silane coupling agent had been added. The water content in 1010 parts by mass of the acid curable resin (III) was 4.5% by mass, and the nitrogen atom content relative to the total amount of the acid curable resin (III) and water was 3.5% by mass. .
Mix and dissolve 1.32 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) in 98.68 parts by mass of the resulting acid-curable resin (III) to which a silane coupling agent has been added, and caking. 100 parts by mass of the agent (containing 1.00% by mass of calcium chloride in terms of anhydride) was obtained.

(Manufacture of sand composition)
A 75 mass% aqueous solution containing 1.0 mass part of the above binder, 67 mass% of xylene sulfonic acid and 8 mass% of sulfuric acid in 100 mass parts of alumina sand (manufactured by Cosmo Co., Ltd., Alsand 350 # Shin sand). 40 parts by mass were added simultaneously and kneaded with a Shinagawa universal stirrer to obtain a sand composition.
In addition, the compounding quantity of the calcium chloride converted into the anhydride with respect to 100 mass parts of alumina sand is 0.031 mass parts.

(Manufacture of test pieces)
The obtained sand composition is filled in a wooden piece for test piece preparation in which a mold having an inner diameter of 50 mm and a height of 50 mm is formed under conditions of a temperature of 25 ° C. and a humidity of 55%, and 24 hours have elapsed since the start of curing. The test piece was taken out later.
The obtained test piece was measured for compressive strength and bulk density. Table 3 shows the results.

<Experimental example 2>
Experimental Example 1 3.97 parts by mass of calcium chloride dihydrate (CaCl ₂ · 2H ₂ O) was mixed and dissolved in 96.03 parts by mass of the obtained curable silane coupling agent (III). A sand composition was produced in the same manner as in Experimental Example 1 except that 100 parts by mass of a binder (containing 3.00% by mass of calcium chloride in terms of anhydride) was prepared, and the obtained sand composition was used. Test pieces were manufactured, and compressive strength and bulk density were measured. Table 3 shows the blending amount of calcium chloride in terms of anhydride for each result and 100 parts by mass of alumina sand.

<Experimental example 3>
Experimental Example 1 6.62 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved in 93.38 parts by mass of the obtained curable silane coupling agent (III). A sand composition was produced in the same manner as in Experimental Example 1 except that 100 parts by mass of a binder (containing 5.00% by mass of calcium chloride in terms of anhydride) was prepared, and the obtained sand composition was used. Test pieces were manufactured, and compressive strength and bulk density were measured. Table 3 shows the blending amount of calcium chloride in terms of anhydride for each result and 100 parts by mass of alumina sand.

<Experimental example 4>
Experimental Example 1 10.60 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved in 89.40 parts by mass of the obtained curable silane coupling agent (III). A sand composition was produced in the same manner as in Experimental Example 1 except that 100 parts by mass of a binder (containing 8.00% by mass of calcium chloride in terms of anhydride) was prepared, and the obtained sand composition was used. Test pieces were manufactured, and compressive strength and bulk density were measured. Table 3 shows the blending amount of calcium chloride in terms of anhydride for each result and 100 parts by mass of alumina sand.

<Experimental example 5>
Experimental Example 1 13.25 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved in 86.75 parts by mass of the acid-curable resin (III) to which the silane coupling agent had been added. A sand composition was produced in the same manner as in Experimental Example 1 except that 100 parts by weight of a binder (containing 10.00% by mass of calcium chloride in terms of anhydride) was prepared, and the obtained sand composition was used. Test pieces were manufactured, and compressive strength and bulk density were measured. Table 3 shows the blending amount of calcium chloride in terms of anhydride for each result and 100 parts by mass of alumina sand.

As apparent from Table 3, in Experimental Examples 1 to 5 in which a binder was prepared in advance using calcium chloride dihydrate and a sand composition was produced using the binder, the strength sufficient as a mold The compressive strength of was shown. Further, the compressive strength tends to increase as the blending amount increases until the blending amount of calcium chloride converted to anhydride with respect to 100 parts by weight of alumina sand is 0.050 part by weight, but the blending amount is 0.080. When it became more than the mass part, it tended to decrease.

Claims (6)

After preparing a mixture by mixing a refractory granular material and sulfonic acid and / or sulfuric acid, mixing the acid curable resin with the mixture, or mixing the calcium chloride solution and / or magnesium chloride solution after mixing A method for producing a self-hardening mold molding sand composition. A method for producing a self- hardening mold molding sand composition, comprising simultaneously mixing a refractory granular material, a sulfonic acid and / or sulfuric acid, an acid curable resin, and a calcium chloride solution and / or a magnesium chloride solution. The acid curable resin is one or more of a condensate or a cocondensate of one or more selected from the group consisting of furfuryl alcohol, phenols and urea and an aldehyde, and furfuryl alcohol. The manufacturing method of the sand composition for self-hardening mold making of Claim 1 or 2 which contains these. The solvent of the said calcium chloride solution and a magnesium chloride solution is a manufacturing method of the sand composition for self-hardening mold making in any one of Claims 1-3 which is 1 type, or 2 or more types chosen from water and alcohol. The compounding quantity of the said calcium chloride solution and / or a magnesium chloride solution is 0.005-0.150 mass part with respect to 100 mass parts of said refractory granular materials in conversion of an anhydride, Any one of Claims 1-4. The manufacturing method of the sand composition for self-hardening mold making described in 2. The claim 1 for making self-hardening foundry molds sand composition produced by the method according to any one of 5 was filled in a mold for casting molds manufacturing, curing the self-hardening mold formation sand composition, manufacture of molds Method.